In the art of magnetic and optical data storage or recording, it is known to provide one or more flat, circular, recording disks that are supported on a motor driven spindle, for rotation at a generally constant velocity about the spindle's center of rotation. When more than one disk is mounted on the spindle, the assembly is called a disk stack or disk pack. It is conventional practice to provide a comb-like head access arm assembly that moves generally radially of the disk stack. Each arm of this assembly (other that the two arms at the extreme ends of the arm assembly) carries two transducing heads. Each of these two heads is positioned to cooperate with the two closely spaced and confronting recording surfaces of the two adjacent disks.
In order to provide efficient packaging of the disk stack, it is desirable that the disks of the stack be closely spaced, thus requiring that the head support arms that penetrate the space between adjacent disks be of a small or thin profile relative to the axial direction of the disk supporting spindle.
High density recording of this type requires that the recording heads be closely spaced relative to the surface of the recording disk. The term "flying head" has been used to describe this positional relationship of only a few microns. This close head to disk spacing must be maintained without head crashes occurring. Usually, this close head flying relationship is provided by the air film that is developed by the rapidly rotating disk, and by the aerodynamic profile of a slider on which the head is mounted.
In disk drives that make use of the superconducting phenomenon, and preferably operate in a substantial vacuum, this air bearing, flying head environment is difficult to achieve. One advantage of the present invention is that this problem is solved.
The present invention makes use of the well known Meissner or magnetic mirror effect, i.e. the property of a superconducting material whereby the material generally blocks the passage of a magnetic flux field through the material. In the case of mixed state superconducting material, small magnetic vortices may thread the surface of the superconducting material. In either case, as a result of the Meissner effect, magnetic flux is bent or guided away from the superconducting material. As a result, a repulsion force is developed between a magnetic field source and the superconducting material.
The present invention provides an electrically energizable coil as a source of a variable magnitude magnetic field. In this way a controllable Meissner or magnetic mirror force is provided. This coil and a superconducting material are associated in a manner to provide a controlled transducing height between a transducing head and the surface of a closely adjacent data recording disk, the magnitude of this flying height being a function of the magnitude of coil energization.
Commonly assigned U.S. Pat. No. 4,843,504, incorporated herein by reference, is of interest in that it discloses and claims superconductive devices useful in disk drives, and more specifically a drive mechanism for positioning a transducing head relative to circular recording media. This head is attached to an arm, and the arm is bearing supported by way of a superconductor layer that cooperates with a magnet in accordance with the Meissner effect. In this way, the arm's bearing assembly, which includes the superconducting layer and the magnet in interfacing relation, operates to support the arm throughout its radial travel relative to the disk.
Commonly assigned patent application Ser. No. 07/336,995, filed Apr. 12, 1989, is a divisional application of above mentioned U.S. Pat. No. 4,843,504, and claims a carriage positioning control concept whereby the magnetic mirror effect of a superconductive material relative to a magnetic field source operates to apply a force to a device on which the superconductor is attached. By placing the superconductor so that it will reflect at least one of the magnetic fields from two different sources, a force balance is obtained, and this force balance is used to position or move a carriage and its read/write head relative to a magnetic recording medium.